Lattice design of the transport system for the bypass line in the storage ring based fully coherent light source

BackgroundThe storage ring-based coherent light source employing angular dispersion-induced microbunching (ADM) can generate high-order harmonic radiation with minimal energy modulation.PurposeThis study aims to design the lattice of transport system for the bypass line that meets geometric layout requirements and achieves high transport efficiency while matching beam optics between the storage ring and the modulation sections.MethodsFirstly, the accelerator toolbox (AT) was employed to design the lattice of the beam transport line to satisfy geometric layout requirements between the storage ring and the energy modulation/demodulation sections. Then, the beam optics functions were matched to ensure high transport efficiency through proper magnetic focusing structure design. Finally, orbit correction schemes were developed and simulated to mitigate effects from misalignment and magnetic field errors.ResultsThe designed beam optics of the transport line satisfies all requirements with maximum horizontal dispersion of 1.03 m. Orbit correction reduces distortion to approximately 4%~5% of the initial values while maintaining corrector strengths below 0.27 mrad. Results of particle tracking simulation with 10 000 macroparticles demonstrate that transmission efficiency is 100% under the vacuum chamber aperture of ±17.5 mm.ConclusionsThe magnetic focusing structure design proposed in this study successfully meets all geometric and optical matching requirements for the bypass line transport system. With proper orbit correction addressing installation and magnetic field errors, the transport system achieves 100% theoretical transmission efficiency while maintaining beam quality for the ADM-based coherent light generation.