Transverse modulation of an electron beam generated in self-modulated laser wakefield accelerator experiments

Area of Science:

• Plasma Physics
• Particle Accelerators
• Laser-Plasma Interactions

Background:

• Laser wakefield acceleration (LWFA) is a promising technique for generating high-quality electron beams.
• Understanding electron beam dynamics, including filamentation and transverse ejection, is crucial for optimizing LWFA performance.

Purpose of the Study:

• To investigate the behavior of low-energy electron beams in a self-modulated laser wakefield accelerator.
• To identify the mechanisms causing electron beam filamentation and radial jet formation.
• To determine the energy threshold at which these phenomena are suppressed.

Main Methods:

• Experimental observation of electron beams generated in a self-modulated laser wakefield accelerator.
• Analysis of electron beam profiles at different energy levels (approximately 300 keV and >900 keV).
• Correlation of beam behavior with laser propagation and plasma interactions, including relativistic self-focusing.

Main Results:

• Low energy electron beams (approx. 300 keV) showed filamentation and deflection, forming radial jets.
• Higher energy electron beams (E>900 keV) exhibited suppressed filamentation and jets, resulting in smooth, copropagating beams.
• Electron beam filamentation is attributed to laser beam filamentation in plasma via relativistic self-focusing.
• Radial jets are likely caused by transverse electron ejection due to wakefield structure and space charge effects.

Conclusions:

• Electron beam morphology in LWFA is strongly energy-dependent.
• Relativistic self-focusing and wakefield structure significantly influence electron beam quality and stability.
• Controlling electron beam behavior requires careful management of laser and plasma parameters to achieve desired beam characteristics.