# Enhanced laser radiation pressure acceleration of protons with a gold cone-capillary

## TL;DR

This paper proposes a gold cone-capillary scheme to enhance laser-driven proton acceleration, achieving higher energy, better beam quality, and improved collimation through simulation, with potential applications in fusion and medicine.

## Contribution

The study introduces a novel gold cone-capillary target design that significantly improves proton acceleration efficiency and beam quality compared to previous methods.

## Key findings

- Achieved monoenergetic proton peak energy of ~1.51 GeV
- Produced proton beams with divergence angle ~1.0°
- Identified optimal capillary length for maximum acceleration efficiency

## Abstract

A scheme with gold cone-capillary is proposed to improve the protons acceleration and involved problems are investigated by using the two-dimensional particle-in-cell simulations. It is demonstrated that the cone-capillary can efficiently guide and collimate the protons to a longer distance and lead to a better beam quality with a dense density $\geq10n_c$, monoenergetic peak energy $E_k \sim 1.51~\mathrm{GeV}$, spatial emittance $\sim0.0088~\mathrm{mm}~\mathrm{mrad}$ with divergence angle $\theta \sim 1.0^{\circ}$ and diameter $\sim 0.5\mathrm{\mu m}$. The enhancement is mainly attributed to the focusing effect by the transverse electric field generated by the cone as well as the capillary, which can prevent greatly the protons from expanding in the transverse direction. Comparable to without the capillary, the protons energy spectra have a stable monoenergetic peak and divergence angle near to $1.0^{\circ}$ in longer time. Besides, the efficiency of acceleration depending on the capillary length is explored, and the optimal capillary length is also achieved. Such a target may be benefit to many applications such as ions fast ignition in inertial fusion, proton therapy in medicine and so on.