Positron acceleration in plasma wakefield accelerators using plasma columns

Plasma accelerators produce extremely large fields, enabling compact accelerators. Owing to these ultra-high accelerating gradients, application of plasma accelerators to the next generation of linear electron-positron colliders has attracted considerable interest. The ability to accelerate and transport high-quality positron beams is critical to realizing this application. In this invited talk, a novel concept for positron acceleration in beam-driven plasma wakefield accelerators (PWFAs) will be presented. This concept relies on a finite radius plasma, or plasma column, to control the wakefields driven by a charged-particle beam, generating a region with focusing and accelerating fields for positron beams [1]. It has been demonstrated, via theory and particle-in-cell simulations, that low emittance and energy spread beams can be accelerated with optimal beam loading providing a path to collider-relevant positron beam parameters [2]. Critical to this application is the stability against misalignment and asymmetries of the drive electron beam and the trailing positron beam propagating along the plasma column. Recent work has demonstrated the intrinsic stability of a drive [3] and trailing [4] beams propagating in the plasma channel, and the stabilization mechanisms will be discussed in this talk. The effect of a non-zero plasma temperature and realistic, non-ideal plasma column profiles will be shown. Finally, experimental implementations of this concept at beam test facilities will also be discussed.