Direct Observation of Spatiotemporal Dynamics of Short Electron Bunches in Storage Rings

Area of Science:

• Physics
• Synchrotron Radiation Science
• Terahertz (THz) Science

Background:

• Short electron bunches in synchrotron radiation facilities generate powerful terahertz (THz) coherent synchrotron radiation (CSR).
• Understanding THz CSR pulse dynamics is crucial for advanced applications.

Purpose of the Study:

• To directly observe and characterize the pulse shapes and dynamics of picosecond electron bunch-induced THz CSR.
• To experimentally verify theoretical predictions regarding the interplay of physical processes governing THz CSR emission.

Main Methods:

• Utilized a high-sensitivity, recently developed photonic time stretch detector for single-shot THz recordings.
• Conducted experiments at the SOLEIL storage ring facility.
• Achieved picosecond resolution for direct observation of THz pulse shapes and dynamics.

Main Results:

• Observed distinct THz pulse dynamics dependent on electron bunch charge.
• Below a critical charge, a broadband THz comb (identical pulses) was observed, attributed to short bunch lengths.
• Above the critical charge, emission was dominated by self-organized drifting structures.

Conclusions:

• Experimental results directly confirm theoretical models of THz CSR emission.
• Demonstrated the transition in THz CSR characteristics from a coherent comb to self-organized structures based on electron bunch charge.
• Highlighted the capability of advanced detectors for studying ultrafast phenomena in synchrotron radiation.