Electron bunch length measurements from laser-accelerated electrons using single-shot THz time-domain interferometry

Area of Science:

• Plasma physics
• Particle acceleration
• Ultrafast science

Background:

• Laser-plasma wakefield accelerators promise high peak currents and ultrashort electron bunches.
• Direct measurement of these ultrashort electron bunch durations in single-shot experiments remains a challenge.

Purpose of the Study:

• To directly measure the pulse duration of laser-accelerated electron bunches in a single-shot experiment.
• To compare the electron bunch duration with the drive laser pulse duration and plasma period.

Main Methods:

• Utilized Terahertz (THz) time-domain interferometry for precise duration measurements.
• Employed a ZnTe-based electro-optical sampling setup.
• Used a 0.5 J, 45 fs, 800 nm laser system for electron acceleration.

Main Results:

• Successfully measured the ultrashort duration of laser-accelerated electron bunches.
• Determined the electron bunch duration to be approximately 32 fs (FWHM), with a 90% upper confidence level of 38 fs.
• Demonstrated that the electron bunch duration is shorter than the drive laser pulse but comparable to the plasma period.

Conclusions:

• The study provides the first direct, single-shot measurement of ultrashort electron bunch durations from laser-plasma wakefield accelerators.
• The measured bunch durations are consistent with theoretical expectations related to the plasma period.
• This measurement technique is crucial for understanding and optimizing laser-plasma electron acceleration.