Optimization of SASE operation for an X-ray free-electron laser Using multiple objective evolutionary algorithms

Abstract

Performance of Self Amplifed Spontaneous Emission (SASE) operation for an X-ray Free-Electron Laser (FEL), is optimized by Multiple Objective Evolutionary Algorithms (MOEA). Different types of hybrid planar undulators are considered to achieve 0.5 Å ≤ λ_FEL ≤ 1.5 Å wavelength range. This demand is regarded as a continuous optimization problem, and hence, an evolutionary algorithm is designed to find optimal FEL performance parameters. An encoding scheme comprising of undulator period (λ_u) and undulator gap (g) is adopted here to find optimal values for saturation power (P_sat) and λ_FEL subject to several physical constraints on λ_u and g such as the ratio of g/λ_u and L_sat. It is shown that MOEA gives optimal solutions for estimation of L_sat with plausible P_sat values.