| High voltage DC photoelectron guns generating beams of 100s of kV are the sources of choice for a wide array of linear accelerators. The beam's brightness is the principal figure of merit for DC gun-driven, GeV-scale synchrotron light sources and meter-scale ultrafast electron diffraction beamlines alike. Irrespective of the machine size, the beam brightness is limited by the parameters of the source: the extraction field and voltage, the drive laser 3D pulse shape, and the intrinsic momentum spread of the electrons leaving the photoemitting material. This thesis describes a new experimental DC gun and beamline constructed at Cornell which has demonstrated the state of the art in each of these parameters. Concepts to allow next generation photoguns to simultaneously achieve higher photocathode fields and total voltages are discussed. To conclude the thesis, a calculation of the fundamental limit on photoemitted beam brightness is given, which arises in cold, dense beams for which strong individual electron interactions result in beam heating. |
