A "lighthouse" laser-driven staged proton accelerator allowing for ultrafast angular and spectral control

TL;DR

This paper introduces a novel laser-driven proton acceleration scheme called 'lighthouse' that enables ultrafast, angular, and spectral control of proton beams by employing a two-stage process for precise energy spectrum tailoring.

Contribution

The paper presents a new staged acceleration method that produces narrowly collimated, high-energy proton beams with controllable spectral and angular properties, advancing laser-plasma acceleration technology.

Findings

Achieves narrow cone emission of high-energy protons.

Enables spectral tailoring of proton beams.

Uses a two-stage process with rapid rear surface motion.

Abstract

Compact laser-plasma acceleration of fast ions has made great strides since its discovery over two decades ago, resulting in the current generation of high-energy ($\geq 100\,\rm MeV$) ultracold beams over ultrashort ($\leq 1\,\rm ps$) durations. To unlock broader applications of these beams, we need the ability to tailor the ion energy spectrum. Here, we present a scheme that achieves precisely this by accelerating protons in a "lighthouse" fashion, whereby the highest-energy component of the beam is emitted in a narrow cone, well separated from the lower-energy components. This is made possible by a two-stage interaction in which the rear surface of the target is first set into rapid motion before the main acceleration phase. This approach offers the additional advantages of leveraging a robust sheath acceleration process in standard micron-thick targets and being optically controllable.