Simulation of the LBNL scaled final focus experiment

Abstract

In the Scaled Final Focus Experiment at LBNL, the beam dynamics of the HIBALL-II final focus system are studied by scaling its beam parameters down to values suitable for laboratory experiments. The final focus system is based on vacuum ballistic focusing, in which the beam first expands and is subsequently focused onto a small spot. Particle-in-cell simulations using the WARP code were done to understand the behavior of the beam as measured in the experiment. In order to closely resemble the final focus system under consideration, the experimental conditions were replicated accurately in the simulation. Special attention was given to the non-ideal effects present in the experiment, such as fringe fields, image charges, and chromatic aberrations. It was shown that simulations can be used to determine which of these effects are likely to significantly affect the beam, and which are not.