Enhancing laser-driven proton acceleration by using micro-pillar arrays at high drive energy

TL;DR

This paper demonstrates that using micro-pillar arrays as targets in high-power laser interactions significantly enhances proton acceleration by increasing hot-electron production and energy conversion efficiency, compared to standard planar targets.

Contribution

The study introduces vertically aligned metallic micro-pillar arrays as novel targets that improve laser-driven proton acceleration at high laser intensities.

Findings

Enhanced hot-electron production with micro-pillar targets

Increased maximum proton energies and particle numbers

Simulation confirms higher laser energy conversion efficiency

Abstract

The interaction of micro- and nano-structured target surfaces with high-power laser pulses is being widely investigated for its unprecedented absorption efficiency. We have developed vertically aligned metallic micro-pillar arrays for laser-driven proton acceleration experiments. We demonstrate that such targets help strengthen interaction mechanisms when irradiated with high-energy-class laser pulses of intensities $\sim$ $10^{17-18}$ W/cm$^2$. In comparison with standard planar targets, we witness strongly enhanced hot-electron production and proton acceleration both in terms of maximum energies and particle numbers. Supporting our experimental results, two-dimensional particle-in-cell simulations show an increase in laser energy conversion into hot electrons, leading to stronger acceleration fields. This opens a window of opportunity for further improvements of laser-driven ion acceleration systems.