MAXIV Photocathode Gun Laser System Specification and Diagnostics

The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running without major issues for more than 3 years. The laser delivers up to §I{500}{\textmu J} on the cathode at the third harmonic, §I{263}{nm}, via a vacuum laser transport system. To achieve the desired pulse duration of 2–§I10{ps} the laser pulses, originally ~§I{100}{fs} long, are stretched with a prism pair and the resulting §I{1.5}{ps} pulses stacked by a series of birefringent \textalpha -BBO crystals. Diagnostics consist of photodiodes, spectrometers, and cameras. Longitudinal pulse characterization is done with a cross correlator and a UV FROG.