High efficiency uniform wakefield acceleration of a positron beam using stable asymmetric mode in a hollow channel plasma

TL;DR

This paper demonstrates a novel method for high-efficiency positron acceleration in plasma wakefields using a stable asymmetric mode in a hollow channel, achieving over 30% energy transfer efficiency with narrow energy spread.

Contribution

It introduces a new stable asymmetric wakefield regime in hollow plasma channels for positron acceleration, which was not previously known.

Findings

Over 30% energy transfer efficiency to positrons.

Achieved 1% energy spread in accelerated positrons.

Simulation results confirm stable and efficient positron acceleration.

Abstract

Plasma wakefield acceleration in the blowout regime is particularly promising for high-energy acceleration of electron beams because of its potential to simultaneously provide large acceleration gradients and high energy transfer efficiency while maintaining excellent beam quality. However, no equivalent regime for positron acceleration in plasma wakes has been discovered to-date. We show that after a short propagation distance, an asymmetric electron beam drives a stable wakefield in a hollow plasma channel that can be both accelerating and focusing for a positron beam. A high charge positron bunch placed at a suitable distance behind the drive bunch can beam-load or flatten the longitudinal wakefield and enhance the transverse focusing force, leading to high-efficiency and narrow energy spread acceleration of the positrons. Three-dimensional quasi-static particle-in-cell (PIC) simulations show that over 30% energy extraction efficiency from the wake to the positrons and 1% level energy spread can be simultaneously obtained, and further optimization is feasible.