Field-reversed bubble in deep plasma channels for high-quality electron acceleration

Area of Science:

• Plasma physics
• Laser-driven particle acceleration

Background:

• Laser-driven electron acceleration typically occurs in uniform plasmas.
• Uniform plasmas can lead to optical shocks and etching at the laser front, limiting acceleration efficiency.

Purpose of the Study:

• To investigate hollow plasma channels for laser-driven electron acceleration in the bubble regime.
• To explore the impact of smooth boundaries on laser-plasma interactions and electron energy gain.

Main Methods:

• Simulations of laser propagation and interaction within hollow plasma channels.
• Analysis of plasma density profiles and their effect on bubble dynamics.
• Characterization of accelerated electron beams, including energy spread and monoenergeticity.

Main Results:

• Hollow plasma channels prevent optical shocks and etching, increasing bubble phase velocity and energy gain.
• A plateau in the longitudinal field enables monoenergetic electron acceleration.
• Achieved low energy spread (10⁻³ rms relative uncertainty, 0.3% total).
• Bubble fields adjusted via plasma density profiles to balance laser depletion and dephasing lengths.

Conclusions:

• Hollow plasma channels offer a superior alternative to uniform plasmas for laser-driven electron acceleration.
• Optimized plasma density profiles and ultrashort laser pulses maximize electron energies.
• Derived bubble scaling laws for deep channels provide a basis for future accelerator design.