Generating high quality relativistic electron beams using density downramp injection in plasma wakefields*

In the past few decades plasma wakefield acceleration (PWFA) and laser wakefield acceleration (LWFA) have attracted a lot of interest in applications for compact next generation linear colliders and x-ray free-electron-lasers (XFEL). Recently, density downramp injection has been proposed and demonstrated as a controllable injection scheme for generating high quality relativistic electron beams. However, full-3D simulations of plasma-based acceleration schemes can be computationally intensive, sometimes taking millions of CPU-hours. Due to the near azimuthal symmetry in PWFA and LWFA, quasi-3D simulations using a cylindrical geometry are computationally more efficient than 3D Cartesian simulations since only the first few azimuthal harmonics and are needed to capture the 3D physics of most problems. We present quasi-3D results from downramp injection simulations using OSIRIS to generate electron beams with ~ 10²⁰  A/m²/rad² peak brightness and low absolute slice energy spread of ~O(0.1) MeV. We also compare the accuracy of these results against 3D simulations and present results from parameter scans of downramp injection using the quasi-3D algorithm to optimize beam quality. Preliminary results of other injection schemes will also be presented