Beam optical system of the polarized electron source of the Amsterdam pulse stretcher AmPS

The beam optical system of a Polarized Electron Source (PES) is described. The PES is used for nuclear physics experiments with internal gas targets on the MEA-AmPS acceleration facility at NIKHEF. The PES beam optical system consists of a 100 keV photoelectron gun, a 100 keV beam line, and a 400 keV post-accelerator. Both the electrostatic and the beam trajectory calculations in the gun have been performed with the SAM code. To calculate the beam envelope in the PES beam line the MAD code was used. The input for MAD was obtained from beam trajectory calculations in the gun, extrapolated for a beam with non-zero initial emittance. Results of the beam line performance test are given.