creator Wisniewski, Eric E. advisor Spentzouris, Linda A new high-charge RF gun is now operating at the Argonne Wakefield Accelerator (AWA) facility at Argonne National Laboratory (ANL). The 1.5 cell 1.3 GHz gun uses a Cesium telluride photocathode driven with a 248 nm laser to provide short-pulse, high charge electron beams for the new 75 MeV drive beamline. The high-gradient RF gun (peak field on the cathode > 80MV/m) is a key piece of the facility upgrade. The large Cs2Te photocathode (diameter > 30 mm) was fabricated in-house. The photo-injector will be used to generate high-charge, short pulse, single bunches (Q > 100 nC) and bunch-trains (Q>1000 nC) for wakefield experiments, typically involving dielectric-loaded accelerating structures. Details of the photocathode fabrication process and the results of associated diagnostic measurements are presented, including QE measurements and work function measurements performed with a Kelvin probe. Field-emitted dark current from the Cs2Te cathode was measured during RF conditioning and characterized. Fowler-Nordheim plots of the data are presented and compared to similar measurements made using a copper cathode in the initial phase of conditioning. The results for cesium telluride exhibited non-linear regions within the Fowler-Nordheim plots similar to previous experimental results for other p-type semiconductors. Results of quantum efficiency (QE) studies are presented with the cathode operating in both single and bunch-train modes. QE uniformity and lifetime studies are presented. During commissioning, the cesium telluride photocathode produced bunch-charge of 100 nC, breaking the previous record. No evidence of bunch-train position-dependence of QE was found when generating four-bunch trains with total charge up to 200 nC. Submitted by Liana Khananashvili (khananashvili@iit.edu) on 2014-11-17T18:39:41Z No. of bitstreams: 1 WisniewskiThesisfinal.pdf: 2600318 bytes, checksum: 704a25e7e611cc5bd8e97ef368629bd9 (MD5) Made available in DSpace on 2014-11-17T18:39:41Z (GMT). No. of bitstreams: 1 WisniewskiThesisfinal.pdf: 2600318 bytes, checksum: 704a25e7e611cc5bd8e97ef368629bd9 (MD5) Previous issue date: 2014-05 PH.D in Physics, May 2014 2014 2014-05 http://hdl.handle.net/10560/3350 en Dissertation born digital application/pdf In Copyright http://rightsstatements.org/page/InC/1.0/ Restricted Access PHYS / Physics Illinois Institute of Technology Affiliated department