Advanced photoinjector laser and microwave technologies. Final report

An overview of the design parameters of the compact, high gradient, high luminosity X-band (8.568 GHz) photoinjectorfacility currentlybeing developed as a collaborative effort between LLNL and UC Davis, is followed by a more detaileddescription of each of its major subsystems: X-band rf gun, GHz repetitionrate synchronouslymodelocked AIGaAs quantum well laser oscillator,and 8-pass Ti:Alz03chirpedpulse laser amplifier. The photoinjectoruses a high quantum efficiency(-5%) CszTe photocathode, and will be capable of producinghigh charge (> 1 nC), relativistic(5 MeV), ultrashort (< 1 ps) electron bunches at 2.142 GHz repetition rate in burst mode (100 photoelectron bunches). Design studies indicatethat a normalizedmm transvemeem”tiance~ = 0.75 n mm-mrad is possibleat 0.1 nC charge, while 2.5 n mm-mrad canbe obtained at 1 nC. A complete status reportof our progressin the development and implementationof the design discussedherein is then given, togetherMM initialexperimentaldata concerning the performanceof the 15 MW SIJK X-band klystronampliiir. Fina!ly,the phase noise and jiier characteristicsof the laser and rf systems of the h~h gradient X-band photoinjectorhave been measured experimentally.In this case, the laser oscillatoris a self-modelockedTtianium:Sapphiresystem operatingat the 108th subharmonic of the rf gun. The X-band signal is produced from the laser by a phase-locked dielectric resonanceoscillator,and amplifiedby a pulsed lWT. A compakon between the TVW phase noise and the fields excited in the rf gun demonstratesthe filteringeffect of the high Q cavity resonant structure,thus indicatingthat the rf gun can be used as a master oscillator,and could be energized by either a magnetronor a cross-fieldamplifier.