Cold and high power tests of a multibunch X-band photoinjector

Summary form only given. A high brightness X-band photoinjector, capable of multi-bunch operation at GHz repetition rates, and developed as a collaboration between the UC Davis DAS and SRRC, is reaching the initial phase of high power tests. The photoinjector was designed using SUPERFISH, PARMELA, POISSON, URMEL and HFSS. Cold test showed excellent agreement between the design parameters and the RF characteristics of the prototype. In addition, the phase noise and jitter characteristics of the laser and RF systems of the high gradient X-band photoinjector have been measured experimentally. The laser oscillator is a self-modelocked Titanium:Sapphire system operating at the 108th subharmonic of the RF gun. The X-band signal is produced phase-locking a dielectric resonance oscillator to the laser oscillator, and amplified by a pulsed TWT. A comparison between the TWT phase noise and the fields excited in the RF gun demonstrates the filtering effect of the high Q structure, thus indicating that the RF gun can be used as a master oscillator, and could be energized by either a magnetron or a cross-field amplifier. Finally, high power tests are currently underway, including the 20 MW SLAC klystron, the RF system, and the RF gun. In particular, dark current, spatial, temporal, and momentum beam distributions will be fully characterized.