Efficient injection of radiation-pressure-accelerated sub-relativistic protons into laser wakefield acceleration based on 10 PW lasers

TL;DR

This paper introduces a hybrid laser-driven proton acceleration method combining radiation pressure acceleration and laser wakefield acceleration, utilizing 10 PW lasers to produce multi-GeV proton beams with improved efficiency.

Contribution

It presents a novel two-stage scheme that enhances proton acceleration by tailoring plasma density and leveraging high-power laser pulses.

Findings

Efficient generation of multi-GeV proton beams demonstrated.

Decreasing plasma density prolongs proton-wake phase synchronization.

Hybrid scheme improves proton acceleration efficiency.

Abstract

We propose a hybrid laser-driven ion acceleration scheme using a combination target of a solid foil and a density-tailored background plasma. In the first stage, a sub-relativistic proton beam can be generated by the radiation pressure acceleration in the intense laser interaction with the solid foil. In the second stage, this sub-relativistic proton beam is further accelerated by the laser wakefield driven by the same laser pulse in a near-critical-density background plasma with a decreasing density profile. The propagating velocity of the laser front and the phase velocity of the excited wakefield wave are effectively lowered at the beginning of the second stage. By decreasing the background plasma density gradually from near critical density along the laser propagation direction, the wake travels faster and faster while it accelerates the protons. Consequently, the dephasing between the protons and the wake is postponed, and an efficient wakefield proton acceleration is achieved. This hybrid laser-driven proton acceleration scheme can be realized by using ultrashort laser pulses at the peak power of 10 PW for the generation of multi-GeV proton beams.