Shot-to-shot electron beam pointing instability in a nonlinear plasma bubble

Area of Science:

• Plasma Physics
• Accelerator Physics
• Quantum Electrodynamics

Background:

• Electron beam pointing jitter (EBJ) is a significant challenge in laser wakefield acceleration (LWFA).
• Variations in laser and plasma parameters cause EBJ, but the underlying physics of its growth within plasma waves is not fully understood.

Purpose of the Study:

• To theoretically investigate the fundamental physics governing EBJ growth in LWFA plasma bubbles.
• To identify and analyze the mechanisms responsible for amplifying EBJ.

Main Methods:

• Developed analytical models for electron trajectory, pointing angle, and EBJ based on electron momentum equations.
• Verified theoretical findings through numerical simulations.
• Investigated the influence of radiation reaction on EBJ.

Main Results:

• Identified intrinsic betatron oscillation as an amplifier for EBJ.
• Discovered two key amplification processes: linear resonance in wobbling bubbles and parametric resonance in breathing bubbles.
• Quantified the growth rates and resonance conditions for these processes.
• Showed that fluctuations in laser (strength, focus, CEP) and plasma (density, profile) parameters initiate EBJ.

Conclusions:

• The dynamics of the plasma bubble dictate EBJ evolution.
• Understanding resonant amplification mechanisms is crucial for mitigating EBJ.
• This research clarifies EBJ dynamics, paving the way for enhanced LWFA stability and broader applications.