Chaotic dynamics in X-ray free-electron lasers with an optical undulator

Area of Science:

• Plasma Physics
• Accelerator Physics
• Nonlinear Dynamics

Background:

• Optical undulators offer miniaturized X-ray free-electron laser (FEL) sources with higher gain and lower electron beam energy requirements compared to traditional magnetostatic undulators.
• The interaction between intense relativistic electron beams and optical undulators is a complex nonlinear phenomenon that can induce chaotic dynamics.

Purpose of the Study:

• To investigate the chaotic motions of relativistic electrons within X-ray FELs utilizing an optical undulator and a magnetized ion-channel background.
• To identify the key parameters influencing the transition from regular to chaotic electron trajectories and explore potential chaos control mechanisms.

Main Methods:

• Derivation of electron motion equations from the interaction region's Hamiltonian.
• Utilizing simulation results to analyze the dependence of chaotic dynamics on parameters like beam density, magnetic field strength, and ion-channel density.
• Employing bifurcation diagrams and Poincaré maps to visualize and distinguish between regular and chaotic electron motions.

Main Results:

• The transition from orderly to chaotic electron motion is sensitive to specific parameters including beam density, axial magnetic field strength, ion-channel density, and pump laser undulator intensity.
• Critical parameter values were identified that trigger the onset of chaos.
• Bifurcation diagrams and Poincaré maps successfully illustrated the origin of chaos and differentiated between electron motion types.

Conclusions:

• The study provides insights into controlling chaotic electron dynamics in optical undulator-based X-ray FELs.
• This research contributes to the development of more stable and efficient X-ray light sources with applications in basic sciences, medicine, and industry.