We present the results of multi-objective genetic algorithm optimizations of a potential single shot ultra fast electron diffraction beamline utilizing a 225 kV dc gun with a novel cryocooled photocathode system and buncher cavity. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at sample location have been performed for three different sample radii: 50, 100, 200 microns, for two final bunch charges: 100k and 1000k electrons. Analysis of the solutions is discussed, as are the effects of disorder induced heating. In particular, a coherence length per rms spot size of 0.27 nm/micron was obtained for a final bunch charge of 100k electrons and final rms bunch length of approximately 100 fs. For a final charge of 1000k electrons the cryogun produces a coherence length per rms spot size of 0.1 nm/micron for an rms bunch length of 100-200 fs and final spot size of 50 micron. These results demonstrate the viability of using genetic algorithms in the design and operation of ultrafast electron diffraction beamlines.
@article{arxiv.1510.07738,
title = {Multi-objective Optimizations of a Novel Cryo-cooled DC Gun Based Ultra Fast Electron Diffraction Beamline},
author = {C. Gulliford and A. Bartnik and I. Bazarov},
journal= {arXiv preprint arXiv:1510.07738},
year = {2016}
}