Collimated protons accelerated from an overdense gas jet irradiated by a 1 micron wavelength high-intensity short-pulse laser

TL;DR

This study demonstrates shock-driven proton acceleration from a near-critical density hydrogen gas jet using a high-intensity 1-micron laser, producing monoenergetic and low-divergence proton beams with potential for future laser-driven ion sources.

Contribution

It reveals a robust shock acceleration mechanism in near-critical gas jets at 1-micron wavelength, offering a new pathway for monoenergetic proton beam generation.

Findings

Observation of shock-driven monoenergetic proton beams

Proton energies around a few MeV

Robustness of the acceleration mechanism

Abstract

We have investigated proton acceleration in the forward direction from a near-critical density hydrogen gas jet target irradiated by a high intensity (10^18 W/cm^2), short-pulse (5 ps) laser with wavelength of 1.054 micron. We observe the signature of shock acceleration driven by the laser pulse, leading to monoenergetic proton beams with small divergence in addition to the commonly used electron-sheath driven proton acceleration. The proton energies we obtained are modest (~MeV), but prospects for improvement are offered through tailoring the gas jet density profile. Also, we observe that this mechanism is very robust in producing those beams and thus can be considered as a future candidate in laser-driven ion sources driven by the upcoming next generation of multi-PW near-infrared lasers.