Laser-plasma proton acceleration with a combined gas-foil target

TL;DR

This study explores a novel gas-foil target for laser-plasma proton acceleration, demonstrating how gas density influences laser intensity and proton energy, with potential for higher energy gains through self-focusing effects.

Contribution

The paper introduces a new gas-foil target design and uses 3D PIC simulations alongside experiments to analyze laser pulse propagation and proton acceleration mechanisms.

Findings

Nearly seven-fold increase in laser peak intensity due to gas self-focusing.

Proton energies depend strongly on laser energy transmission through the gas.

High gas densities cause laser energy depletion and pulse distortion, reducing proton energies.

Abstract

Laser-plasma proton acceleration was investigated in the Target Normal Sheath Acceleration (TNSA) regime using a novel gas-foil target. The target is designed for reaching higher laser intensity at the foil plane owing to relativistic self-focusing and self compression of the pulse in the gas layer. Numerical 3D particle-in-cell (PIC) simulations were used to study pulse propagation in the gas, showing a nearly seven-fold increase in peak intensity. In the experiment, maximum proton energies showed high dependence on the energy transmission of the laser through the gas and a lesser dependence on the size and shape of the pulse. At high gas densities, laser energy depletion and pulse distortion suppressed proton energies. At low densities, self-focusing was observed and comparable or higher proton energies were measured with the gas.