• C. Vicario, R. Ganter, C.P. Hauri, S. Hunziker, F. Le Pimpec, C. Ruchert, T. Schietinger, A. Trisorio
  PSI, Villigen

For high brigthness photocathode RF gun, proper laser pulses should be used to generate the photocurrent. Transverse uniformity and longitudinal laser flat top profile are predicted to improve the electron beam brigthness. Moreover the laser stability and its sub-ps synchronicity respect to accelerating field are essential for stable and reliable operation. Finally the intrinsic emittance, which is the ultimate limit for the beam emittance, could be tuned by varying the laser photon energy. For this purpose, we developed a mJ frequency tripled Ti:sapphire laser, tunable within 260-283 nm range. Dependence of the intrinsic emittence and of the quantum efficiency with the photon energy has been measured and compared to theory for various metallic photocathode. In this paper the R&D activities aiming at the photocathode laser for the future SwissFEL project are reported.