Plasma lens-based beam extraction and removal system for plasma wakefield acceleration experiments

Plasma wakefield acceleration represents one of the most promising techniques able to overcome the limits of conventional rf technology and make possible the development of compact accelerators. With respect to laser-driven schemes, the particle beam-driven scenario is not limited by diffraction and dephasing issues; thus, it allows one to achieve larger acceleration lengths. Nevertheless, one of the most prominent drawbacks occurs at the end of the acceleration process and consists in the removal of the depleted high-charge driver while preserving the main features (emittance and peak current) of the accelerated witness bunch. Here we present a theoretical study demonstrating the possibility to reach these goals by using an innovative system consisting of an array of beam collimators and discharge capillaries operating as active-plasma lenses. Such a system allows one to extract and transport the accelerated and highly divergent witness bunch and, at the same time, provides for the removal of the driver. The study is completed with a set of numerical simulations conducted for different beam configurations. The physics of the interaction of particles with collimator is also investigated.