Self-stabilizing positron acceleration in a plasma column

TL;DR

This paper demonstrates that a plasma-based positron acceleration scheme, previously thought to be potentially unstable, is inherently stable due to damping mechanisms, enabling high-quality, stable positron acceleration in plasma columns.

Contribution

It reveals that the positron acceleration scheme relying on cylindrical symmetry is inherently stable because of damping mechanisms acting on the witness beam.

Findings

The witness beam experiences damping mechanisms that stabilize the acceleration process.

The scheme remains stable despite potential misalignments of drive and witness beams.

Stable, high-quality positron acceleration is achievable in plasma columns.

Abstract

Plasma accelerators sustain extreme field gradients, and potentially enable future compact linear colliders. Although tremendous progress has been achieved in accelerating electron beams in a plasma accelerator, positron acceleration with collider-relevant parameters is challenging. A recently proposed positron acceleration scheme relying on the wake generated by an electron drive beam in a plasma column has been shown to be able to accelerate positron witness beams with low emittance and low energy spread. However, since this scheme relies on cylindrical symmetry, it is possibly prone to transverse instabilities that could lead, ultimately, to beam break-up. In this article, we show that the witness beam itself is subject to various damping mechanisms and, therefore, this positron acceleration scheme is inherently stable towards misalignment of the drive and witness beams. This enables stable, high-quality plasma-based positron acceleration.