Self-consistent positron creation and acceleration up to a few GeVs in a plasma channel*

Positron acceleration embodies a significant milestone towards the development of a high-energy electron-positron collider. While plasma wakefield acceleration seems a promising way to achieve this goal, it presents limits such as creating and accelerating the beam beforehand, and injecting it with precision in the right phase of plasma wakefield.

A recent numerical investigation suggests a way to both create and accelerate positrons in a compact setup. It relies on the 90-degree interaction of a multi-PW laser with a GeV-class electron beam. Positrons are created via the Breit-Wheeler process and are accelerated in vacuum to a few GeVs by the strong laser field.

In this work, we adapt the aforementioned scheme and accelerate the positrons in a preformed plasma channel via direct laser acceleration. Our simulations include both the self-consistent creation and the acceleration of the positron beam, relying on the quasi-3D version of the Particle-In-Cell code Osiris. We provide estimates for the number of positrons created and deflected by the intense laser pulse, with a special focus on conditions for successful positron injection. The applicability of this scheme in future laser facilities is finally assessed through analytical scaling laws.