Optimization of Plasma-Downramp Profiles in LWFA Staging for Collider Applications*

Plasma-based particle accelerators, offering substantially higher accelerating fields than conventional machines, enable compact designs capable of producing high-charge (> 100 pC) and high-current (> kA) particle beams. Plasma-wakefield accelerators are promising candidates for next-generation TeV-class electron-positron colliders and secondary light sources for studying high-energy physics. Achieving TeV energies necessitates a staging approach with multiple laser-driven plasma accelerators, each preserving low energy spread and beam emittance. A major challenge is maintaining beam emittance across numerous stages to ensure high luminosity in colliders. We present numerical results for the optimization of plasma downramp profiles and inter-stage beam transport in multi-stage plasma accelerators. Simulations use the Beam pLasma & Accelerator Simulation Toolkit (BLAST) and are performed with ensemble optimizations.