First Measurements of Trojan Horse Injection in a Plasma Wakefield Accelerator

Plasma accelerators support accelerating fields of 100's of GV/m over meter-scale distances and routinely produce femtosecond-scale, multi-kA electron bunches. The so called Trojan Horse underdense photocathode plasma wakefield acceleration scheme combines state-of-the-art accelerator technology with laser and plasma methods and paves the way to improve beam quality as regards emittance and energy spread by many orders of magnitude. Electron beam brightness levels exceeding 10²⁰ Am⁻² rad⁻² may be reached, and the tunability allows for multi-GeV energies, designer bunches and energy spreads <0.05% in a single plasma accelerator stage. The talk will present results of the international E210 multi-year experimental program at SLAC FACET, which culminated in successful first demonstration of the Trojan Horse method during FACET's final experimental run in 2016. Enabling implications for applications, including high performance plasma-based 5th generation light sources such as hard x-ray FEL's, for which start-to-end simulations are presented, and for high energy physics are discussed.