The transverse and longitudinal beam characteristics of the PHIN photo-injector at CERN

A new photo-injector, capable to deliver a long pulse train with a high charge per bunch for CTF3, has been designed and installed by a collaboration between LAL, CCLRC and CERN within the framework of the second Joint Research Activity PHIN of the European CARE program. The demonstration of the high charge and the stability along the pulse train are the important goals for CTF3 and the CLIC drive beam. The nominal beam for CTF3 has an average current of 3.5 A, a 1.5 GHz bunch repetation frequency and a pulse length of 1.27 μs (1908 bunches). The existing CTF3 injector consists of a thermionic gun and a subharmonic bunching system. The PHIN photo-injector is being tested in a dedicated test-stand at CERN to replace the existing CTF3 injector that is producing unwanted satellite bunches during the bunching process. A phase-coding scheme is planned to be implemented to the PHIN laser system providing the required beam temporal structure by CTF3. RF photo-injectors are high-brightness, low-emittance electron sources. One of the main beam dynamics issues for a high brightness electron source, is the optimization of beam envelope behavior in the presence of the space charge force in order to control the beam emittance. Beam based measurements, such as single shot emittance measurement with a multi-slit configuration, have been performed during the commissioning runs in 2008 and 2009. In this work the photo-injector will be describe d and the first beam test results will be presented and compared with simulations.