Abstract:

The Next Generation Light Source (NGLS), a high repetition rate soft x-ray free electron laser (FEL), is one of the top priorities of the LBNL strategic plan. Such a billion-dollar class user facility with its formidable performance will allow for revolutionary advances in many fields of science. In order to operate the NGLS, an extremely high quality (high brightness) electron beam is required, and the ultimate performance of the facility is actually set by the characteristics of the beam right at the source: the electron gun. While high quality electron-guns with moderate repetition rates (~ 100 Hz) already exist (notable example the gun of LCLS, the hard x-ray FEL at SLAC), the same it is not true for the MHz repetition rate case required by the NGLS, in fact such a gun presently does not exist. In response to this need, our group at LBNL initiated the Advanced Photo-injector EXperiment (APEX) to develop a novel-scheme photo-injector based on a room temperature 187 MHz RF cavity operating in continuous wave (CW) mode and capable of delivering MHz electron bunches with brightness suitable for x-ray free FEL applications. After an introduction on the NGLS concept, the talk will concentrate on the description of APEX and of its present status and future plans.