Multi-objective Optimizations of a Normal Conducting RF Gun Based Ultra Fast Electron Diffraction Beamline

TL;DR

This paper uses multi-objective genetic algorithms to optimize an ultra fast electron diffraction beamline with a normal conducting RF gun, analyzing emittance, coherence length, and effects of heating for various charge and bunch length scenarios.

Contribution

It introduces a novel application of genetic algorithms for optimizing beamline parameters, considering multiple objectives and physical effects.

Findings

Optimized emittance as a function of bunch charge.

Achieved specific coherence lengths for different bunch lengths.

Demonstrated the viability of genetic algorithms in beamline design.

Abstract

We present the results of multi-objective genetic algorithm optimizations of a potential single shot ultra fast electron diffraction beamline utilizing a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2pi/3 bunching cavity placed between two solenoids. 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 the sample location have been performed for a charge of 1e6 electrons. Analysis of the solutions is discussed, as are the effects of disorder induced heating. In particular, for a charge of $10^6$ electrons and final beam size greater than or equal to 25 microns, we found a relative coherence length of 0.07, 0.1, and 0.2 nm/micron for a final bunch length of approximately 5, 30, and 100 fs, respectively. These results demonstrate the viability of using genetic algorithms in the design and operation of ultrafast electron diffraction beamlines.