High-Efficiency Wakefield Acceleration of Positrons via a Slit Plasma Channel

Abstract

Although plasma-based wakefield acceleration has achieved remarkable success for electrons, efficient positron acceleration remains a long standing challenge, as positrons suffer severe defocusing in the accelerating phases of such structures. Here, we propose a slit plasma wakefield acceleration (SPWA) scheme, in which a relativistic electron beam propagating through a slit channel formed by two parallel plasma slabs excites crossing plasma-electron filamentary structures within the slit, generating intense wakefields tailored to simultaneously provide longitudinal acceleration and transverse focusing for a trailing positron bunch. A theoretical model is developed to characterize the wakefield structure responsible for positron acceleration and focusing. Three-dimensional particle-in-cell simulations validate the model, and demonstrate that the SPWA scheme achieves a positron trapping efficiency of nearly 100%, while maintaining low emittance growth and narrow energy spread for an injected positron beam. These findings establish a new and robust approach to high-efficiency positron acceleration, with promising implications for future compact electron-positron colliders and high-energy positron applications.