High-rep rate photocathode injector for LCLS

A preliminary design of the photocathode RF gun injection system for LCLS 120 Hz operation will be presented in this report. The injection system includes a photocathode RF gun, an emittance compensation solenoid magnet, an Mg cathode, a laser and laser beam delivery system and electron beam diagnostics. The photocathode RF gun for 120 Hz LCLS operation is based on the BNL gun IV with several improvements, such as better cooling and vacuum pumping capabilities, and accurate alignment. The thermal calculation of the RF gun, computer simulation of its performance, and both transverse and various longitudinal laser pulse shaping techniques will be presented.