Synchronous post-acceleration of laser-driven protons in helical coil targets by controlling the current dispersion

TL;DR

This paper presents a method to enhance laser-driven proton acceleration by controlling current dispersion in a two-stage helical coil, achieving significant energy gains and enabling higher proton energies with ultrashort laser pulses.

Contribution

It introduces a novel two-stage helical coil scheme to synchronize electric fields with protons, significantly improving post-acceleration efficiency.

Findings

Proton energy gain is increased by 4 times with optimized parameters.

Protons can reach 45 MeV with hundreds-terawatt lasers.

Potential to exceed 100 MeV proton energy with petawatt lasers.

Abstract

Post-acceleration of protons in helical coil targets driven by intense, ultrashort laser pulses can enhance the ion energy by utilizing the transient current originating from the self-discharging of the targets. The acceleration length of the protons can exceed a few millimeters, and the accelerating gradient is in the order of GeV/m. How to ensure the synchronization of the accelerating electric field with the protons is a crucial problem for an efficient post-acceleration. In this paper, we study how the electric field mismatch induced by the current dispersion affects the synchronous acceleration of the protons. We propose a scheme using a two-stage helical coil to control the current dispersion. With optimized parameters, the energy gain of protons is enhanced by 4 times. And it is expected that the proton energy would reach 45 MeV using a hundreds-terawatt laser, or over 100 MeV using a petawatt laser, by controlling the current dispersion.