Meter-Scale Terahertz-Driven Acceleration of a Relativistic Beam

Area of Science:

• Physics
• Accelerator Science
• Quantum Electronics

Background:

• Terahertz (THz) radiation offers high accelerating gradients for compact accelerators.
• Limited interaction lengths (millimeters) due to synchronism challenges between THz pulses and electron beams have hindered progress.

Purpose of the Study:

• To implement a novel scheme for simultaneous group and phase velocity matching.
• To enable meter-scale inverse free-electron laser (IFEL) interactions.
• To demonstrate the application of laser-based THz sources for relativistic electron beam manipulation.

Main Methods:

• Simultaneous group and phase velocity matching of single-cycle THz radiation with relativistic electron beams.
• Utilizing a magnetic undulator for meter-scale IFEL interaction.
• Employing a laser-based THz source with modest pulse energies (≤1 μJ).

Main Results:

• Achieved energy modulations of up to 150 keV in the electron beam.
• Demonstrated meter-scale IFEL interaction, overcoming previous length limitations.
• Successfully utilized the THz source for relativistic electron beam bunch-length compression and time-stamping.

Conclusions:

• The developed scheme effectively synchronizes THz radiation with electron beams over meter-scale distances.
• Laser-based THz sources can be effectively used for advanced electron beam manipulation.
• This work paves the way for compact, high-gradient accelerators and novel beam diagnostics.