Low divergence proton beams from a laser-plasma accelerator at kHz repetition rate

TL;DR

This paper demonstrates the generation of low divergence, high-repetition-rate proton beams from laser-plasma interactions, with detailed experimental and simulation studies indicating potential for practical applications.

Contribution

It introduces a method to produce low divergence proton beams at kHz repetition rates using femtosecond laser pulses on solid targets, supported by experimental and theoretical analysis.

Findings

Proton beams with up to 100 pC charge and 0.48 MeV energy were generated.

Beam divergence as low as 3 degrees was achieved.

Numerical simulations agree with experimental results and suggest practical applications.

Abstract

Proton beams with up to 100 pC bunch charge, 0.48 MeV cut-off energy and divergence as low as a $3^{\circ}$ were generated from solid targets at kHz repetition rate by a few-mJ femtosecond laser under controlled plasma conditions. The beam spatial profile was measured using a small aperture scanning time-of-flight detector. Detailed parametric studies were performed by varying the surface plasma scale length from 8 to 80 nm and the laser pulse duration from 4 fs to 1.5 ps. Numerical simulations are in good agreement with observations and, together with an in-depth theoretical analysis of the acceleration mechanism, indicate that high repetition rate femtosecond laser technology could be used to produce few-MeV protons beams for applications.