Modeling an emittance-dominated elliptical sheet beam with a -dimensional particle-in-cell code

Modeling a 3-dimensional (3-D) elliptical beam with a 2 1 2 -D particle-in-cell (PIC) code requires a reduction in the beam parameters. The 2 1 2 -D PIC code can only model the center slice of the sheet beam, but that can still provide useful information about the beam transport and distribution evolution, even if the beam is emittance dominated. The reduction of beam parameters and resulting interpretation of the simulation is straightforward, but not trivial. In this paper, we describe the beam parameter reduction and emittance issues related to the initial beam distribution. As a numerical example, we use the case of a sheet beam designed for use with a planar traveling-wave amplifier for high power generator for RF ranging from 95 to 300 GHz [Carlsten et al., IEEE Trans. Plasma Sci. 33 (2005) 85]. These numerical techniques also apply to modeling high-energy elliptical bunches in RF accelerators.