Beam-line optimization based on realistic electron-optics 3D field-maps implementation provides high-quality e-beam via a dogleg section

Abstract

A 6 MeV hybrid RF e-gun is currently driving a THz FEL in Ariel University. Ultra-fast electron diffraction (UED) experimental plans are currently in progress in the center, and therefore, a secondary parallel beam line is required. The addition of a secondary beamline using a single e-gun can be achieved using a dogleg section. However, the high-quality beam parameters such as emittance and electron bunch duration are significantly distorted after passing a dispersive section, such as a dogleg section, making the e-beam quality insufficient for UED experiments. In this paper, we suggest an optimization method, for the reconstruction of the beam quality after the dogleg using realistic quad-fields and sextupoles. Full 3D general particle tracer simulations of this secondary beamline were used in the optimization procedure using realistic field-maps and fringe fields of the quadrupoles, which were designed in-house, and their 3D field-maps were exported using computer simulation technology. Significantly improved beam parameters were obtained using the real quadrupoles field profile combined with an optimization procedure using a large number of electron optical optimization variables.