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

TL;DR

This paper demonstrates a stable, high-quality plasma cathode using density-downramp injection in a beam-driven plasma wakefield accelerator, achieving high charge, energy, and efficiency at DESY.

Contribution

It introduces a novel, drift-free plasma cathode method with high injection efficiency and operational stability in a beam-driven plasma wakefield accelerator.

Findings

Achieved electron beams with up to 105 pC charge and a few percent energy spread.

Tunable acceleration fields up to 2.7 GV/m were demonstrated.

Identified sources of jitter and strategies for performance enhancement.

Abstract

This paper describes the utilization of beam-driven plasma wakefield acceleration to implement a high-quality plasma cathode via density-downramp injection in a short injector stage at the FLASHForward facility at DESY. Electron beams with charge of up to 105 pC and energy spread of a few percent were accelerated by a tunable effective accelerating field of up to 2.7 GV/m. The plasma cathode was operated drift-free with very high injection efficiency. Sources of jitter, the emittance and divergence of the resulting beam were investigated and modeled, as were strategies for performance improvements that would further increase the wide-ranging applications for a plasma cathode with the demonstrated operational stability