The Performance of Seeded Free-Electron Lasers Through Dispersion Strength Tuning

TL;DR

This paper explores how tuning dispersion strength affects the performance of seeded free-electron lasers, analyzing the relationships among bunching, pulse energy, and stability through theory, simulation, and experiments.

Contribution

It offers new insights into optimizing seeded FELs by examining dispersion effects, highlighting trade-offs between pulse energy and coherence.

Findings

Optimal dispersion strength correlates with maximum bunching.

Pulse splitting impacts energy stability and coherence.

Guidelines for tuning FEL performance are provided.

Abstract

Over the last decade, external seeded free electron lasers (FELs) have achieved significant advancements across various disciplines, progressively establishing themselves as indispensable tools in fields ranging from fundamental science to industrial applications. The performance of seeded FELs is critically dependent on the quality of the frequency up-conversion process. Optimized conditions for seeded FELs are typically considered as the maximization of the bunching factor. This paper discusses alternative perspectives on the optimization criteria for seeded FELs by analyzing the impact of dispersion strength on their overall performance. We investigate the relationship among the required dispersion strength for achieving the maximum bunching factor, maximum pulse energy, and optimal energy stability through theoretical analysis, simulation calculations, and experimental explorations. Additionally, the direct observation of pulse splitting emphasizes the consideration of trade-off between pulse energy and temporal coherence in seeded FELs. These results provide valuable insights and practical guidance for controlling the pulse characteristics of seeded FELs, contributing to the tuning and optimization of FEL facilities.