Conditioning of a new gun cavity towards 60 MV/m at PITZ

A new L-band photoelectron gun (prototype 3.2) has been installed for use with a 10 MW klystron at the Photo- Injector Test facility in Zeuthen (PITZ). This gun has been conditioned starting in April 2007 up to a maximum gradient of about 60 MV/m. The gun was tuned for resonance at 1.3 GHz, and stable operation has been achieved with 100 mus RF pulses with a repetition rate of 10 Hz. Over certain periods the gun has been conditioned at high gradient with RF pulses of 400 mus, and conditioning has to be continued at longer pulse lengths up to 700 mus. Maximum power in the gun has been achieved with a new RF waveguide phase shifter with a 2pi range. Dark current measurements have been performed with several cathodes, including uncoated molybdenum, electropolished uncoated molybdenum, and cesium telluride. Also, the first photoelectrons have been accelerated with the new gun cavity.