FLASHForward X-2: Towards beam quality preservation in a plasma booster

Abstract

a b s t r a c tBeam quality preservation in the external injection scheme is one of the key missing milestones towards staging of plasma-wakefield accelerators, a prerequisite for their utilisation in particle physics or other applications requiring high energy beams. This topic will be studied at FLASHForward, a unique beam-driven plasma wakefield acceleration facility currently under construction at DESY (Hamburg, Germany), in the frame of the FLASHForward X-2 experiment. High-quality 1 GeV-class electron beams from the free-electron laser FLASH with m-emittances, kA-scale currents, and less than 100 fs durations will be utilised to generate driver-witness pairs by using a mask in a dispersive section. In this contribution the physics case and the current status of the FLASHForward X-2 experiment are reviewed. The experimental installation is described, with a focus on the electron beamline. Electron beam dynamics and particle-in-cell simulations are presented.

Progress of the FLASHForward X-2 high-beam-quality, high-efficiency plasma-accelerator experiment

“…First installations of the FLASHForward beamline started in 2015 and continued until 2018, as described in Ref. [18]. Sections for beam extraction, compression and dispersion cancellation, matching and final focusing, as well as post-plasma spectrum diagnostics were completed, which allowed first experiments [19] in a short (33-mm-long) plasma cell.…”

FLASHForward: plasma wakefield accelerator science for high-average-power applications

“…However, other favourable beam properties such as emittance -essential for collider facilities in order to maximise final focus luminosities -must also be conserved. The FLASHForward X-2 experiment [24] is designed to answer these questions.…”

Controlled density-downramp injection in a beam-driven plasma wakefield accelerator

“…Witness beams can be injected into the plasma wakefield either from an external source or internally by the trapping of ambient plasma electrons. Research on external injection methods has predominantly concentrated on maximizing energy transfer from the drive to the witness beam while preserving other beam parameters, such as emittance and energy spread [14,15]. Internal injection methods with extremely high electric-field gradients (GV/m) have the potential to generate beams with exceptionally high quality.…”