Far-field constant-gradient laser accelerator of electrons in an ion channel

TL;DR

This paper predicts a novel laser acceleration mechanism where electrons gain ultra-relativistic energies in an ion channel by interacting with both a laser pulse and a decelerating electric field, maintaining high-amplitude betatron oscillations for efficient energy transfer.

Contribution

It introduces a new constant-gradient laser acceleration scheme leveraging a decelerating electric field to sustain betatron oscillations and enable continuous energy gain.

Findings

Electrons can reach ultra-relativistic energies via this mechanism.

High-amplitude betatron oscillations are maintained by the decelerating field.

Multiple harmonics of betatron motion can be utilized.

Abstract

We predict that electrons in an ion channel can gain ultra-relativistic energies by simultaneously interacting with a laser pulse and, counter-intuitively, with a decelerating electric field. The crucial role of the decelerating field is to maintain high-amplitude betatron oscillations, thereby enabling constant rate energy flow to the electrons via the direct laser acceleration mechanism. Multiple harmonics of the betatron motion can be employed. Injecting electrons into a decelerating phase of a laser wakefield accelerator is one practical implementation of the scheme.