SLAC, Menlo Park, California, USA
DESY, Hamburg, Germany
LBNL, Berkeley, California, USA
SLAC, Menlo Park, California, USA
INFN/LASA, Segrate (MI), Italy
Science needs in the last decade have been pushing the accelerator community to the development of high repetition rates (MHz/GHz-class) linac-based schemes capable of generating high brightness electron beams. Examples include X-ray FELs; ERLs for light source, electron cooling and IR to EUV FEL applications; inverse Compton scattering X-ray or gamma sources; and ultrafast electron diffraction and microscopy. The high repetition rate requirement has profound implications on the technology choice for most of the accelerator parts, and in particular for the electron gun. The successful performance of the GHz room-temperature RF photo-injectors running at rates <~ 100 Hz, cannot be scaled up to higher rates because of the excessive heat load that those regimes would impose on the gun cavity. In response to this gun need, we have developed at Berkeley the VHF-Gun, a lower-frequency room-temperature RF photo-gun capable of CW operation and optimized for the performance required by MHz-class X-ray FELs. The Advanced Photo-injector EXperiment (APEX) was funded and built for demonstrating the VHF gun performance, and the results of its last phase of commissioning are presented.
LBNL, Berkeley, California, USA
SLAC, Menlo Park, California, USA
LCLS-II is a proposed high-repetition rate (>1 MHz) Free Electron Laser (FEL) X-ray light source, based on a CW, superconducting linac, to be built at SLAC National Accelerator Laboratory. The injector technology is based on a high-repetition rate RF photoinjector gun developed as part of the Advanced Photoinjector Experiment (APEX) at Lawrence Berkeley National Laboratory. Exploration of the injector design settings is performed using a multiobjective genetic optimizer to optimize the beam quality at the injector exit (~100 MeV). In this paper, we describe the current status of LCLS-II injector design optimization, with a focus on the sensitivity of the optimized solutions to the beam energy at the injector exit, which is constrained by the requirements of the downstream laser heater system.
SLAC, Menlo Park, California, USA
The planned LCLS-II FEL has an average beam power of up to 1.2 MW and a repetition rate of up to 1 MHz, both of which entail serious challenges for beam halo collimation. This paper summarizes the efforts to assess the proposed collimation system. The undulator section is specifically focused on due to its high loss sensitivity (maximal 12 mW). This proceedings concentrate on field emissions of the gun. Different dark current distribution, linac configurations and simulation programs were used to increase assurance of the results. Filled phase-space tracking further supplemented an independent prove of the collimation system effectiveness and expands to include beam-halo originating from different sources than the gun.