SLAC, Menlo Park, California
SLAC's Advanced Computations Department (ACD) has developed the parallel Finite Element 3D electromagnetic code suite ACE3P for modeling of complex accelerator structures. The Particle-In-Cell module Pic3P was designed for simulations of beam-cavity interactions dominated by space charge effects. Pic3P solves the complete set of Maxwell-Lorentz equations self-consistently and includes space-charge, retardation and boundary effects from first principles. In addition to using conformal, unstructured meshes in combination with higher-order Finite Element methods, Pic3P also uses causal moving window techniques and dynamic load balancing for highly efficient use of computational resources. Operating on workstations and on leadership-class supercomputing facilities, Pic3P allows large-scale modeling of photoinjectors with unprecedented accuracy, aiding the design and operation of next-generation accelerator facilities. Applications include the LCLS RF gun and the BNL polarized SRF gun.
PSI, Villigen
One possible electron source for the PSI-XFEL is the Low Emittance Gun (LEG), which is currently under development at PSI. It consists of a pulsed DC gun, which operates at 500 keV and has the option of using either a photo cathode or a field emitter array. The gun is followed by a pulsed in-vacuum solenoid and a two frequency cavity, not only used to accelerate the beam but also to create a highly linear energy correlation required for ballistic bunching. All components are rotationally symmetric, so a full particle-in-cell simulation of the setup using 2 1/2 D MAFIA, including space charge, wake fields and beam loading effects, shows the base line performance. The low emittance beam, which propagates in a large part of the setup at relatively small energies of around 500 kEV, is rather sensitive to small perturbations in the fields. So we also investigated the effect of mechanical misalignments on the beam quality using the 3D in-house code CAPONE.