Proton energy enhancement by optimizing a laser pulse profile.

Area of Science:

• Plasma Physics
• Laser-Plasma Interactions
• Particle Acceleration

Background:

• Laser prepulses inevitably create low-density plasma targets, limiting proton acceleration.
• Achieving high-energy proton beams requires overcoming limitations in laser contrast and target density.

Purpose of the Study:

• To propose a new scheme for enhancing proton energy using a two-peak laser pulse.
• To overcome the limitations imposed by low-density plasma targets and laser contrast.

Main Methods:

• Utilizing particle-in-cell (PIC) simulations to model laser-plasma interactions.
• Employing a two-peak laser pulse: P1 (lower intensity) to form a dense target, followed by P2 (higher intensity) for acceleration.
• Simulating circularly polarized (CP) laser pulses with specific intensities, durations, and focal spot sizes.

Main Results:

• Protons with a cut-off energy of 940 MeV were achieved using the proposed scheme.
• The two-peak pulse scheme resulted in a 340 MeV increase in proton cut-off energy compared to a single pulse.
• The scheme successfully compressed the low-density plasma target into a denser state for efficient acceleration.

Conclusions:

• The proposed two-peak laser pulse scheme effectively enhances proton energy by overcoming prepulse-induced low-density plasma targets.
• This method offers a feasible experimental approach to achieving higher proton energies, surpassing current limitations.
• The findings have significant implications for laser-driven particle acceleration and related applications.