Start-to-end optimization framework of free-electron lasers driven by laser wakefield accelerators

A start-to-end framework is thus essential for coherent optimization of the full process. Here, we establish such a framework, integrating LWFA beam generation, transport, and FEL interaction within a unified loop.

By incorporating beamline configuration in the optimization, it enables consistent assessment of overall FEL performance. Using this framework, a representative parameter set suitable for extreme ultraviolet FEL operation is obtained. The optimized beam exhibits a mean energy of approximately 500 MeV, a charge of 34 pC, and a relative energy spread of 0.4% (FWHM).