  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
